The debate about explanations in social and human sciences is multifaceted. In my view the fundamental dispute concerns deep metaphysical convictions about the relations between individuals and society and how one conceives a human being, a person. The dividing line goes between those who conceive individual human beings as basically independent of society and other persons, (which seems to be implicit in the liberal political tradition), and those who rejects this view, holding that a human being is constituted by its social relations. The former view is taken for granted by thinkers in the liberal tradition, and latter view is clearly expressed by Marx and is also stated by Aristotle. These views give rise to different methodological views regarding scientific explanations; those who conceive man to be constituted by its social relations are naturally methodological collectivists, while those who think of people as independent individuals are methodological individualists. The difference concerns what is explanans and explanandum: collectivists hold that explanans are social structures and explanandum consists of individual’s actions, whereas methodological individualists have it the other way round: explanans consists of individual’s actions and explanandum consists of social structures and facts.
One could always ask for an explanation of that which explains, so explanation chains may continue backwards without limit. Hence the dispute between methodological individualists and methodological collectivists is a dispute about where to begin an explanation.
Functional explanations are also discussed and it is argued, following Elster, that these are reducible either to action explanations of causal explanations.